Problem with Motherboard

[NegroEspia]

Hello everyone 
Well 2 years ago I bought a GA-Z77X-UD3H for my build and 9 mouths beforce it started giving problems with the RAM slots. I bougth always Avant 4 GB 1600 Mhz Modules (they are the only one on my country) and replaced the old ones and no success. Alaways giving debug 55 no matter the orden of the RAM, it only worked with 1-3 or just 1 slots.
So I thought it was a MB problem and I bought 1 day ago a new one: AsRock Z77 Extreme4 and reinstalled all my build.
Now this MB gives me debug 55 that stands for "Memory not installed" but i checked thousand times the modules and they are correctly connected to the MB. I bought 3 new RAM slots (same brand for the same reason. The only one on my country) and probed again and the problem persist.

I don't know what to do, the debug 55 is always there on both brands.

My specs are:
MB's: GA-Z77x-UD3H (old) and AsRock Z77 Extreme4 (new)
CPU: Intel I7-3770K
GPU: Nvidia GTX 660 Ti
PSU: Super Flower 850 Watts, Bronce
RAM: 7 Modules of Avant 4 GB 1600 Mhz
Case: Cooler Master K380

Thanks for reading and sorry for the bad english.